There has been proposed an image forming apparatus such as a laser printer, in which a developer cartridge detachably attached to a developing cabinet of a developing device.
For example, JP-A-7-225514 discloses a configuration in which a developer cartridge is detachably attached to a casing of a developing device.
A first opening is formed in the developer cartridge, and a second opening is formed in the casing of the developing device. When the developer cartridge is attached to the casing of the developing device to bring the first and second openings into mutual communication, toner accommodated in the developer cartridge can be supplied to the developing device by way of the first and second openings.